Utilization of Scanning Acoustic Microscope (SAM) to prove the existence of stress relaxation in woven composite

摘要

Nonlinear ultrasonic techniques have shown the prominent potential for assessing progressive damage occurred inthe composite materials in their fatigue life cycles. Stress relaxation in composite material is being measured in two ways,in-situ analysis (on-line technique) using Lamb waves and Off-line technique using pressure wave (Scanning AcousticMicroscope). In this article, the progressive damage was investigated by a set of fatigue loading experiments on wovencomposite samples followed by a specific duration of stress relaxation in room temperature condition. A quantitativemeasure of stress relaxation is determined using Scanning Acoustic Microscope for a fatigue cycle of 225000 with theloading frequency of 10 Hz. To prove this claim, a well-established reduced order nonlinear state of Lamb wave due tostress-relaxation was compared with SAM data analysis. A good agreement between these two techniques is reportedherein.